[−][src]Struct rand_isaac::isaac64::Isaac64Rng
A random number generator that uses ISAAC-64, the 64-bit variant of the ISAAC algorithm.
ISAAC stands for "Indirection, Shift, Accumulate, Add, and Count" which are the principal bitwise operations employed. It is the most advanced of a series of array based random number generator designed by Robert Jenkins in 19961.
ISAAC-64 is mostly similar to ISAAC. Because it operates on 64-bit integers instead of 32-bit, it uses twice as much memory to hold its state and results. Also it uses different constants for shifts and indirect indexing, optimized to give good results for 64bit arithmetic.
ISAAC-64 is notably fast and produces excellent quality random numbers for non-cryptographic applications.
In spite of being designed with cryptographic security in mind, ISAAC hasn't
been stringently cryptanalyzed and thus cryptographers do not not
consensually trust it to be secure. When looking for a secure RNG, prefer
Hc128Rng
from the rand_hc
crate instead, which, like ISAAC, is an
array-based RNG and one of the stream-ciphers selected the by eSTREAM
Overview of the ISAAC-64 algorithm:
(in pseudo-code)
Input: a, b, c, s[256] // state
Output: r[256] // results
mix(a,i) = !(a ^ a << 21) if i = 0 mod 4
a ^ a >> 5 if i = 1 mod 4
a ^ a << 12 if i = 2 mod 4
a ^ a >> 33 if i = 3 mod 4
c = c + 1
b = b + c
for i in 0..256 {
x = s_[i]
a = mix(a,i) + s[i+128 mod 256]
y = a + b + s[x>>3 mod 256]
s[i] = y
b = x + s[y>>11 mod 256]
r[i] = b
}
This implementation uses BlockRng64
to implement the RngCore
methods.
See for more information the documentation of IsaacRng
.
Bob Jenkins, ISAAC and RC4 ↩
Trait Implementations
impl Clone for Isaac64Rng
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pub fn clone(&self) -> Isaac64Rng
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pub fn clone_from(&mut self, source: &Self)
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impl Debug for Isaac64Rng
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impl RngCore for Isaac64Rng
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pub fn next_u32(&mut self) -> u32
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pub fn next_u64(&mut self) -> u64
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pub fn fill_bytes(&mut self, dest: &mut [u8])
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pub fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>
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impl SeedableRng for Isaac64Rng
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type Seed = <Isaac64Core as SeedableRng>::Seed
Seed type, which is restricted to types mutably-dereferencable as u8
arrays (we recommend [u8; N]
for some N
). Read more
pub fn from_seed(seed: Self::Seed) -> Self
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pub fn seed_from_u64(seed: u64) -> Self
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Create an ISAAC random number generator using an u64
as seed.
If seed == 0
this will produce the same stream of random numbers as
the reference implementation when used unseeded.
pub fn from_rng<S: RngCore>(rng: S) -> Result<Self, Error>
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Auto Trait Implementations
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,